A solar cell contains a semi-conductor structure and metallization on surface areas of the structure, to transmit an electric potential difference between the areas that arises from conversion of light in the semi-conductor structure. The operational lifetime of the solar cell depends on the susceptibility of the solar cell to corrosion when it is exposed to various weather conditions. To optimize the operational lifetime it is desirable to measure the susceptibility to corrosion.
Electrochemical noise (ECN) measurements are a known method to test materials for susceptibility to corrosion. Known ECN measurements comprise measurement of noise properties of the spontaneous electric current through a connection between electrodes made of the material under test, when the electrodes are immersed in an electrolyte bath. ECN measurements may also comprise measurement of noise properties of spontaneous electric voltage between the electrodes, or between an electrode made of the material under test and a reference electrode.
The material that is used for metallization of solar cells could per se be tested by means of ECN measurements. However, it has been found that this does not give a reliable prediction of the effect of susceptibility to corrosion on the operational lifetime. The geometric properties of the metallization, such as its thickness and layout, and the way in which the material is applied have been found to affect the operational lifetime.
The inventors propose to apply ECN measurements to solar cells with metallization to test the susceptibility of the metallization of solar cells to corrosion. Conventional ECN measurements can be applied to solar cells by immersing solar cells in an electrolyte bath and measuring currents through the metallization into the bath and/or voltages on the metallization. However, it has been found these measurements are affected by active behavior of the solar cells, such as photo-currents.